title: Influence of adenosine analogs on morphine tolerance and dependence in mice.
abstract: A number of adenosine agonists were investigated for possible actions on tolerance to morphine withdrawal in mice. The induction of tolerance to a sustained release preparation of morphine was assessed by measuring the analgesic effect induced by a test dose of the drug. The concomitant treatment with L- and D-phenylisopropyl adenosine, (L- and D-PIA), cyclopentyladenosine (CPA) or chloroadenosine (CADO) during the period of morphine absorption did not alter the induction of the process. In contrast cyclohexyladenosine (CHA) significantly decreased the intensity of tolerance. The administration of naloxone 30 hrs, after the priming dose of morphine induced an intense withdrawal reaction. The intensity of the abstinence syndrome was decreased by the administration of L-PIA, CHA or CADO; CPA and D-PIA were ineffective. These results suggest that adenosine analogs may interfere with the known morphine effects on calcium disposition in nerve terminals.
authors.affiliation: Departamento de Ciencias Fisiológicas, Facultad de Ciencias Biológicas y de Recursos Naturales, Universidad de Concepción, Chile.
authors.forename: A
authors.initials: A
authors.lastname: Germany
authors.forename: M
authors.initials: M
authors.lastname: Villar
authors.forename: L
authors.initials: L
authors.lastname: Quijada
authors.forename: E
authors.initials: E
authors.lastname: Contreras
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004361:Drug Tolerance; D051379:Mice; D009021:Morphine Dependence / Q000188:drug therapy* / Q000378:metabolism; D009270:Naloxone / Q000494:pharmacology; D013375:Substance Withdrawal Syndrome / Q000209:etiology
chemical_list: D009270:Naloxone; D000241:Adenosine; D002118:Calcium